I use Avast as my realtime antivirus, running Malwarebytes and Superantispyware manually once a week. I use Zonealarm for my firewall. I've been using this setup for 6 months with no issues so far. I previously used Bitdefender for years with ZERO infections, but their latest version went from being stripped down using hardly any resources to mega-bloated. I never had any luck with Norton, McCafee, or Trend Micro.